Sponge



FIG. 1 is a perspective view showing the new design for a sponge;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines in the drawings are shown for illustrative purposes only and form no part of the claimed design. 

CLAIM The ornamental design for a sponge, as shown and described. 